JP2570096B2 - System time matching method and system time matching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for reflecting a system time of a computer in a system of a plurality of computers connected by a network in a system time of another computer to make them coincide with each other.

[0002]

2. Description of the Related Art Conventionally, in order to match the system time between a plurality of computers constituting a network system, the time of a system clock of an arbitrary computer of the network system is transmitted as time data to another computer. In another computer, the time required for transmitting the time data is added to the received time data, and the system clock of the other computer is set during system operation.

For example, in Japanese Patent Application Laid-Open No. 63-213013, a maximum transmission delay time is adopted as the transmission time of the time data, and the time set in the system clock of the other computer is set to the time specified in the transmission message. Synchronize throughout the network.

In Japanese Patent Application Laid-Open No. 1-250119,
As the transmission time of the time data, a value measured immediately before the transmission of the time data is employed, and the time set in the system clock of the other computer is immediately performed after the transmission of the data.

[0005]

In the conventional system time matching method, in a network system constituted by a plurality of computers connected via a communication line,
In the method of matching the time of the system clock between computers, since each computer corrects the system time while the system is operating, the time flow may be interrupted or duplicated. At this time, if there is a process that is activated depending on the time, the process is not activated or activated twice.

An object of the present invention is to solve such a problem and to provide a method and apparatus for correcting the system time without causing inconsistency in the flow of time.

[0007]

According to the present invention, there is provided a computer network system comprising a first computer and a second computer connected via a communication line, wherein the first computer is used. In the system time matching method for matching the time of the second system clock of the second computer with the time of the first system clock of the first computer, the first computer is connected to the first computer via the communication line. A first time at an arbitrary time of the first system clock of the computer is transmitted to the second computer, and the second computer transmits the first time and the second time of the second computer. A difference between a second time read from the second system clock and a second time read from the second system clock is obtained, and this difference is calculated as the difference between the first system clock and the second system clock. During a start-up process at the time of restarting the system of the second computer, a sum of the difference time and a third time read from the second system clock is obtained. The new system time is set for the second system clock, the startup process is continued, and the time between the computers is reasonably matched with each other.

Further, according to the present invention, a first system used in a computer network system constituted by a first computer and a second computer connected via a communication line, wherein the first computer has In a system time matching device that matches the time of a second system clock of the second computer with the time of a clock, the first computer is configured to control the second computer of the first computer via the communication line. Means for transmitting a first time at an arbitrary time of the first system clock to the second computer, wherein the second computer has the first time and the second time held by the second computer. Means for determining a difference between the second system clock and the second time read from the second system clock, and calculating the difference between the first system clock and the second system clock. Means for storing the difference time as a difference time between the second computer and a third time read from the second system clock during a startup process at the time of restarting the system of the second computer. Means for setting the sum as a new system time, setting the new system time with respect to the second system clock, and further continuing the start-up processing, so that the time between the computers can be made to match without difficulty. Is obtained.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention. 2 and time reading means 12-1 and 12
-2, difference time calculation means 13-1, 13-2, difference time storage means 14-1, 14-2, set time calculation means 15-1, 15-2, time setting means 16-1, 16-
2 and time transmission / reception means 17-1 and 17-2.

FIG. 2 is a time-series processing explanatory diagram showing the flow of processing when adjusting the time of the system clock 11-2 of the computer 2 to the time of the system clock 11-1 of the computer 1. The operation of this embodiment will be described below with reference to the drawings.

In order to match the time of the system clock 11-2 of the computer 2 with the time of the system clock 11-1 of the computer 1, first, the system clock 11-1 of the computer 1 is set. The time is read by the time reading means 12-1 and is read as the standard system time T.
The standard system time T11 is transmitted to the computer 2 by the time transmitting / receiving means 17-1.

In the computer 2, the standard system time T11
Is received by the time transmitting / receiving means 17-2, and the difference time calculating means 13-2 obtains the difference between the time T21 read by the time reading means 12-2 and the time transmitting / receiving means 17-2, and calculates the difference time ΔT Call.

ΔT = T 21 −T 11 (1) Further, the difference time storage unit 14-2 stores the difference time ΔT obtained by the difference time calculation unit 13-2 until the next system startup.

Set time calculation means 15 performed at the time of start processing when the system is stopped and the system is started again
-2, the time reading means 12-2 reads the time T
The sum of the error time ΔT and the error time ΔT stored by the difference time storage means 14-2 is obtained, and this is set as a new system time T22 ′.

T22 ′ = T22 + ΔT (2) In the time setting means 16-2, the set time calculation means 15
-2, the new system time T22 'is set in the system clock 11-2, and the startup processing is continued.

[0017]

As described above, the present invention corrects the system time between the computers constituting the network system without causing inconsistency in the flow of time and without affecting the processing during system operation. And the reliability of the system is greatly improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a flowchart of an embodiment of the present invention.

[Explanation of symbols]

 1, 2 Computer 11-1, 11-2 System clock 12-1, 12-2 Time reading means 13-1, 13-2 Difference time calculation means 14-1, 14-2 Difference time storage means 15-1, 15 -2 set time calculating means 16-1, 16-2 time setting means 17-1, 17-2 time transmitting / receiving means 18 communication line

Continuation of the front page (56) References JP-A-61-194940 (JP, A) JP-A-59-72547 (JP, A) JP-A-2-59809 (JP, A) JP-A-2-226410 (JP) JP-A-4-175913 (JP, A) JP-A-2-41513 (JP, A) JP-A-62-49555 (JP, A) JP-A-58-19587 (JP, A) 59-9732 (JP, A) JP-A-4-182806 (JP, A)

Claims (2)

(57) [Claims] 1. A computer network system comprising a first computer and a second computer connected via a communication line, wherein the first computer has the first system clock at the time. In a system time matching method for matching the time of a second system clock of a second computer, the first computer is connected to the first system clock of the first computer via the communication line. Transmitting a first time at an arbitrary point in time to the second computer, wherein the second computer transmits the first time and the second
Calculating the difference between the second time read from the second system clock of the computer, and storing the difference as the difference time between the first system clock and the second system clock. During a start-up process at the time of restarting the system of the computer, a sum of the difference time and a third time read from the second system clock is obtained, the sum is set as a new system time, and the new system time is set as the new system time. Set for the second system clock, continue the startup process,
A system time matching method wherein the time between computers is reasonably matched. 2. A computer network system comprising a first computer and a second computer connected via a communication line, wherein the first computer has the first system clock at the time. In a system time matching device for matching the time of a second system clock of a second computer, the first computer is connected to the first system clock of the first computer via the communication line. Means for transmitting a first time at an arbitrary time to the second computer, wherein the second computer transmits the first time and the second time
Means for determining a difference between the second time read from the second system clock of the computer, and means for storing the difference as a difference time between the first system clock and the second system clock. Means for obtaining a sum of the difference time and a third time read from the second system clock during a startup process at the time of restarting the system of the second computer; and setting the sum as a new system time. Setting the new system time with respect to the second system clock;
A system time matching apparatus, further comprising means for continuing a start-up process, wherein the time between computers is reasonably matched with each other without difficulty.